The Rendezvous and Proximity Operations Program displays and controls capabilities as tools for situational awareness

Abstract

The idea for the Rendezvous and Proximity Operations Program (RPOP) was conceived by a small group of engineers at NASA's Johnson Space Center (JSC). RPOP was part of the tools and technologies implemented for the first Shuttle-Mir rendezvous and docking. Since that time RPOP was used on over 60 missions and became an essential tool for Shuttle rendezvous operations. RPOP serves three main functions: as guidance and navigation software, displays-and-controls mechanism, and situational-awareness tool. This document visits many of the on-orbit firsts for manned spaceflight that were demonstrated in RPOP, with particular focus on the displays and controls and situational awareness aspects. The underlying guidance and navigation algorithms are not exposed. Simultaneous comparison of sensor data from multiple sources, differentiation between multiple three-dimensional trajectories, at-a-glance determination of attitude and location via RPOP's 3D orbiter model, and near-real time updates of guided and unguided trajectory prediction constitute a subset of the RPOP functionality that is detailed. A discussion of the way that RPOP has influenced pilot-in-the-loop behavior for proximity operations, exemplified by the repeatability of mission-to-mission proximity operations trajectories, is presented. Furthermore, many of the concepts that have proven to work well in RPOP have become de facto standards for displays and controls for new manned programs. Astronauts have come to expect the same familiar and effective situational awareness displays to be made available in the Orion Multi-Purpose Crew Vehicle (MPCV); this expectation has driven the design of the next-generation of displays. For example, formal on-orbit handling-qualities assessments of MPCV have all included a RPOP-type display providing key information to the pilots. The lessons learned during the RPOP development and flight experience are not to be taken lightly, but rather ought to be fastidiously applied to future programs since they allow for reuse of proven guidance and navigation display concepts and flight techniques for on-orbit operations.